Hi,
I actually race world cups and know exactly what you are observing. Skin choice is an art and science. We will study the race course profile and plan exact skins for each climb to maximize what we need. A lot of racers use 59 width skins and only 62 for steeper icy sections. We also have different length skins some quit short and some up to a foot and a half behind our rear bindings. We generally hot wax our skins (google pomoco hot waxing skins for a good video) on how to do this. You are right mileage on skins makes them faster a quick way to help wear in skins is to ski downhill with them if your are in a hurry. So in summary your main tools for making skins quicker:
1. Shorter and less wide
2. waxing to improve waterproofing
3. liquid waxes like you described above
4. wearing them in
Tips to make skins grippier
1. longer and wider
2. Pomoco grip skins instead of race pro
One overlooked factor when watching WC racers is technique often the look glidier because they have world class technique when skinning. We do technical skinning practice often and have coaches who analyze our stride. If you are interested in this consider booking a phone consult or custom coaching. To do this on your own practice skinning in race gear at a nordic Center and video yourself, you will surely pull out things you can improve. Also, consider hoping on classic xc skis and getting a lesson if you have no Nordic background.
Hope this helps!
Kylee